There is an increasing demand to automate mobile machinery that traditionally requires a human operator. There are several reasons for this. Unlike a human operator, automated machinery remains consistently productive regardless of environmental conditions and prolonged work hours. Automated machinery is also ideal for applications where conditions are unsuitable or undesirable for humans. Further, automated machinery enables more accurate operation and compensates for lack of operator skill.
The work cycles of different types of machines may include similar requirements. Some mobile machines, including earth, asphalt, and trash compactors, repeatedly traverse a site until the material is compressed to the desired degree. Other types of mobile machines, such as lawn mowing machinery, traverse an area only once during a work cycle. During autonomous operation, these machines require means to determine their position, the area to be traversed, an optimal path to follow while traversing the area, and means to control their movement while traversing the path.
In the prior art, a site survey is typically conducted manually using line-of-sight optical instruments or other static, point by point measuring techniques. Thereafter, the site is carefully marked with stakes to provide visual cues to the operator of the machinery. Systems for achieving a desired degree of compaction or desired site topography with mobile terrain-shaping and material compacting machinery are disclosed in U.S. Pat. Nos. 5,631,658; 5,493,494; 5,471,391; and 5,646,844. In these patents, the actual site topography is determined on a continual basis using a global positioning system on the machine to provide information regarding the position of the machine in space. Using the position of the machine, the actual topography of the terrain is updated as the machine traverses the work site and the difference between the actual site topography and the desired site topography is determined on a continual basis. The areas where there are differences between the desired and the actual site topography indicate areas where work still needs to be done with the machine. This information is provided to an operator via a real-time graphical display to provide visual cues for operating the machine over a work site. The prior art methods do not, however, disclose means for determining the path or set of paths to be used by a mobile machine that is capable of traversing the work area autonomously. Further, with autonomous machinery, the series of paths must be provided in a manner that is usable by a computer-based planning and navigation system that determines how to steer the machine to follow the paths and how to transition the machine from one path to the next.
Accordingly, the present invention is directed to overcoming one or more of the problems as set forth above.